Solidarity is a value that is practised and shared by the inhabitants at the heart of natural regions, which can become hostile, and consequently they need to help each other to progress better together or simply to survive. In the name of the principle of solidarity, each player in the field of trail-running is asked to prioritise going to the aid of anybody in danger or difficulty wherever they are and in whatever circumstance.

In a more global manner, the participants and players in the trail-running field often show solidarity by making a commitment in favour of environmental, social or societal causes or by helping the underprivileged. Trail-running race organisers implement this principle of responsibility by directly supporting charitable actions and sustainable development; numerous participants “run for a cause” to support the projects of their choice.